Grixis combines red, black, and blue in what is commonly called a shard. These three colors allow for a weird mix of chaos and control strategies, upsetting your opponents' games while keeping your own on track as much as possible
Im not aware of many, or any, equipment cards that have effects triggered by becoming attached or unattached (though Im sure there must be something), so I cant comment on how strong this mechanic will be in the long run
Again, it comes down to the games design
Instead, youre going to want to check the rarity icon on the bottom of the card
I also like this in Hate Bears with enough bodies to pump up and get a Commander Damage kill with level 3
If the player chooses others, each of your other opponents sacrifices a land of their choice